Vertebrate Animal Models of RP59: Current Status and Future Prospects

Retinitis pigmentosa-59 (RP59) is a rare, recessive form of RP, caused by mutations in the gene encoding DHDDS (dehydrodolichyl diphosphate synthase). DHDDS forms a heterotetrameric complex with Nogo-B receptor (NgBR; gene NUS1) to form a cis-prenyltransferase (CPT) enzyme complex, which is required for the synthesis of dolichol, which in turn is required for protein N-glycosylation as well as other glycosylation reactions in eukaryotic cells. Herein, we review the published phenotypic characteristics of RP59 models extant, with an emphasis on their ocular phenotypes, based primarily upon knock-in of known RP59-associated DHDDS mutations as well as cell type- and tissue-specific knockout of DHDDS alleles in mice. We also briefly review findings in RP59 patients with retinal disease and other patients with DHDDS mutations causing epilepsy and other neurologic disease. We discuss these findings in the context of addressing "knowledge gaps" in our current understanding of the underlying pathobiology mechanism of RP59, as well as their potential utility for developing therapeutic interventions to block the onset or to dampen the severity or progression of RP59.

Evaluation of the external validity of a joint structure-function model for monitoring glaucoma progression

The dynamic structure–function (DSF) model was previously shown to have better prediction accuracy than ordinary least square linear regression (OLSLR) for short series of visits. The current study assessed the external validity of the DSF model by testing its performance in an independent dataset (Ocular Hypertension Treatment Study–Confocal Scanning Laser Ophthalmoscopy [OHTS–CSLO] ancillary study; N = 178 eyes), and also on different test parameters in a sample selected from the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study (DIGS/ADAGES). Each model was used to predict structure–function paired data at visits 4–7. The resulting prediction errors for both models were compared using the Wilcoxon signed-rank test. In the independent dataset, the DSF model predicted rim area and mean sensitivity paired measurements more accurately than OLSLR by 1.8–5.5% (p ≤ 0.004) from visits 4–6. Using the DIGS/ADAGES dataset, the DSF model predicted retinal nerve fiber layer thickness and mean deviation paired measurements more accurately than OLSLR by 1.2–2.5% (p ≤ 0. 007). These results demonstrate the external validity of the DSF model and provide a strong basis to develop it into a useful clinical tool.

Combined corneal cross-linking and 320° intrastromal corneal ring segments in progressive keratoconus: one-year results

BACKGROUND

Intrastromal corneal ring segments (ICRS) attain regularization of corneal surface in keratoconus (KC), while collagen cross-linking (CXL) halts or slows its progression. The long-arc 320° rings combined with CXL may have a dual-benefit synergistic effect of surface regularity and progression halt.

METHODS

This was a prospective case series study including eyes with progressive KC. Femto-assisted 320° ICRS implantation and epi-off CXL 8 weeks later were carried out in all cases. Uncorrected (UCVA) and corrected distance visual acuity (CDVA) were assessed using Snellen's chart, while corneal tomography was evaluated using Scheimpflug imaging. Follow-up was carried out 3, 6, and 12 months after the CXL.

RESULTS

Thirty-two eyes of 32 patients with progressive KC were included, 18 males and 14 females, and the mean age was 23.1 years. According to the Amsler-Krumeich classification, four eyes had stage 1 KC, 20 had stage 2 KC, and eight had stage 3 KC, and UCVA and CDVA improved from 0.1 ± 0.15 and 0.2 ± 0.19 to 0.4 ± 0.2 (P>  0.01) and 0.5 ± 0.2 (P>  0.01) respectively at 12 months. Manifest refraction spherical equivalent was reduced from - 5.6 ± 2.3 to - 1.1 ± 1.3 D at 12 months after the procedure (P>  0.01). In addition, maximum keratometry was significantly reduced from 54.8 to 49.3 diopters (P>  0.01), while the asphericity index (Q value) has changed from - 1.4 to - 0.25 (P>  0.01) after 12 months. No significant differences were detected between central (n = 12) and eccentric (n = 20) KC in all outcomes.

CONCLUSION

The 320° ICRS-CXL protocol has improved the visual and the tomographic outcomes at 1 year in our patients with progressive KC. No differences were detected between central and eccentric cases. Further larger studies could ensure the safety profile of the combined protocol.

Difluprednate versus Prednisolone Acetate after Cataract Surgery: a Systematic Review and Meta-Analysis

OBJECTIVE

Topical steroids are the cornerstone in controlling the inflammation after cataract surgery. Prednisolone acetate and difluprednate are the two main products for this purpose. However, it is unclear which one should be used in terms of effectiveness and safety.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline via PubMed, Cochrane Central Register of Controlled Trials, Web of science and clinicaltrials.gov were searched through 10 January 2018, and updated on 20 July 2019, in addition to researching the references' lists of the relevant articles.

ELIGIBILITY CRITERIA

Randomised-controlled trials (RCTs) comparing difluprednate and prednisolone acetate regardless of the dosing regimen used.

DATA EXTRACTION AND SYNTHESIS

Two independent authors assessed the included RCTs regarding the risk of bias using the Cochrane tool. Relevant data were extracted, and meta-analysis was conducted using a random-effects model. The Grading of Recommendations Assessment, Development, and Evaluation approach was used to appraise the evidence quality.

RESULTS

We included six RCTs with 883 patients: 441 received difluprednate and 442 received prednisolone acetate. The evidence quality was graded as moderate for corneal oedema and intraocular pressure and low for anterior chamber (AC) clearance. After small incision cataract surgery, difluprednate was superior in clearing AC cells at 1 week (OR=2.5, p>0.00001) and at 2 weeks (OR=2.5, p=0.04), as well as clearing the AC flare at 2 weeks (OR=6.7, p=0.04). After phacoemulsification, difluprednate was superior in terms of corneal clarity at 1 day (OR=2.6, p=0.02) and 1 week after surgery (OR=1.96, p=0.0007). No statistically significant difference was detected between both agents at 1 month in effectiveness. Also, both agents were safe, evaluated by the ocular hypertension (OR=1.23, p=0.8).

CONCLUSION

With low-to-moderate certainty, difluprednate and prednisolone acetate are safe agents for controlling the inflammation after cataract surgery. Difluprednate showed significant superiority in terms of AC cells and AC flare at 2 weeks postoperatively.

Corneal biomechanics and intraocular pressure assessment after penetrating keratoplasty for non keratoconic patients, long term results

Background

To evaluate corneal biomechanical properties by the Ocular Response Analyzer (ORA) in non keratoconic patients underwent penetrating keratoplasty (PK).

Methods

Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann- correlated intraocular pressure (IOPg), cornea-compensated IOP (IOPcc) using the ORA, and central graft thickness (CGT) were measured in 30 eyes at least two years after penetrating keratoplasty for non keratoconic indications. IOP using the Goldmann applanation tonometer (GAT) was also obtained after compensation for graft thickness and astigmatism.

Results

The mean age of patients was 33.1 ± 10.13 years; indications for PK were herpetic corneal scar (53.3%), corneal stromal dystrophy (23.3%), traumatic corneal opacity (10%), chemical corneal opacity (6.7%), and Fuchs endothelial dystrophy (6.7%). Mean CH and CRF were 8.52 ± 1.81 mmHg, and 8.56 ± 1.59 mmHg, respectively. Mean CGT was 532.43 ± 30 μm. Mean IOP GAT, IOPg, and IOPcc were 11.88 ± 3.66, 14.64 ± 4.08, and 17.27 ± 4.60 mmHg, respectively (P < 0.001). No significant association was found between CGT and IOP readings obtained using either the ORA or GAT. There were significant negative association between CH with both IOP GAT and IOPcc, while CRF had significant positive association with IOPg.

Conclusion

After penetrating keratoplasty for non keratoconic patients, graft biomechanics does not return to average values even 2 years after the operation; moreover, intraocular pressure measurement with ORA gives higher values than thickness compensated GAT.

Family Medicine in Egypt From Medical Students' Perspective: A Nationwide Survey

PHENOMENON: Attitudes of medical students toward family medicine as a specialty choice can provide information on the future supply of family physicians. Due to the current worldwide shortage of family physicians, these attitudes, with their subsequent effects on the state and dynamics of the healthcare system, are important to investigate.

APPROACH

A web-based questionnaire was sent to 600 medical students, selected by a systematic random sampling technique, in 7 Egyptian medical schools. Participants were surveyed to assess their perception of the family medicine specialty as a future career and explore the impact of different factors, including undergraduate family medicine clerkships, on their attitudes toward family medicine.

FINDINGS

We had a response rate of 75.2% (n = 451). Although 90.7% of students believed in the vital role that family medicine can play in Egypt's healthcare system, only 4.7% showed an intention to choose it as a future career. Students choosing family medicine as a first-career choice were more likely to have a prior contact with family physicians as consumers. Exposure to an undergraduate family medicine curriculum was associated with increased knowledge about family medicine but not the intentions to pursue it as a career. INSIGHTS: Medical students in Egypt have a positive perception of family medicine as an important specialty but low interest in its choice as a future career.